Power management for distributed communication systems, and related components, systems, and methods

ABSTRACT

Power management techniques in distributed communication systems in which the power available at a remote unit (RU) is measured and compared to the power requirements of the RU. Voltage and current are measured for two dummy loads at the RU and these values are used to solve for the output voltage of the power supply and the resistance of the wires. From these values, a maximum power available may be calculated and compared to power requirements of the RU.

RELATED APPLICATION

This application is a continuation of International Application No.PCT/IL14/050766 filed on Aug. 26, 2014 which claims the benefit ofpriority to U.S. Provisional Application No. 61/870,976, filed on Aug.28, 2013, both applications being incorporated herein by reference.

The present application is related to U.S. patent application Ser. No.13/687,457, filed Nov. 28, 2012, entitled “Power Management ForDistributed Communication Systems, and Related Components, Systems, andMethods,” published as U.S. Pub. No. 20140146692 A1, which isincorporated herein by reference in its entirety.

BACKGROUND

The technology of the disclosure relates to managing power in remoteunits in a distributed communication system.

Wireless communication is rapidly growing, with ever-increasing demandsfor high-speed mobile data communication. As an example, so-called“wireless fidelity” or “WiFi” systems and wireless local area networks(WLANs) are being deployed in many different types of areas (e.g.,coffee shops, airports, libraries, etc.). Distributed communications ordistributed antenna systems communicate with wireless devices called“clients,” which must reside within the wireless range or “cell coveragearea” to communicate with an access point device.

One approach to deploying a distributed antenna system involves the useof radio frequency (RF) antenna coverage areas, also referred to as“antenna coverage areas.” Antenna coverage areas can have a radius inthe range from a few meters up to twenty meters as an example. Combininga number of access point devices creates an array of antenna coverageareas. Because the antenna coverage areas each cover small areas, thereare typically only a few users (clients) per antenna coverage area. Thisallows for minimizing the amount of RF bandwidth shared among thewireless system users. It may be desirable to provide antenna coverageareas in a building or other facility to provide distributed antennasystem access to clients within the building or facility. However, itmay be desirable to employ optical fiber to distribute communicationsignals. Benefits of optical fiber include increased bandwidth.

One type of distributed antenna system for creating antenna coverageareas includes distribution of RF communications signals over anelectrical conductor medium, such as coaxial cable or twisted pairwiring. Another type of distributed antenna system for creating antennacoverage areas, called “Radio-over-Fiber” or “RoF,” utilizes RFcommunications signals sent over optical fibers. Both types of systemscan include head-end equipment coupled to a plurality of remote units(RUs), which may include an antenna and may be referred to as a remoteantenna unit or RAU. Each RU provides antenna coverage areas. The RUscan each include RF transceivers coupled to an antenna to transmit RFcommunications signals wirelessly, wherein the RUs are coupled to thehead-end equipment via the communication medium. The RF transceivers inthe RUs are transparent to the RF communications signals. The antennasin the RUs also receive RF signals (i.e., electromagnetic radiation)from clients in the antenna coverage area. The RF signals are then sentover the communication medium to the head-end equipment. In opticalfiber or RoF distributed antenna systems, the RUs convert incomingoptical RF signals from an optical fiber downlink to electrical RFsignals via optical-to-electrical (O/E) converters, which are thenpassed to the RF transceiver. The RUs also convert received electricalRF communications signals from clients via the antennas to optical RFcommunications signals via electrical-to-optical (E/O) converters. Theoptical RF signals are then sent over an optical fiber uplink to thehead-end equipment.

The RUs contain power-consuming components, such as the RF transceiver,to transmit and receive RF communications signals and thus require powerto operate. In the situation of an optical fiber-based distributedantenna system, the RUs may contain O/E and E/O converters that alsorequire power to operate. In some installations, the RU may contain ahousing that includes a power supply to provide power to the RUs locallyat the RU. The power supply may be configured to be connected to a powersource, such as an alternating current (AC) power source, and convert ACpower into a direct current (DC) power signal. Alternatively, power maybe provided to the RUs from remote power supplies. The remote powersupplies may be configured to provide power to multiple RUs. It may bedesirable to provide these power supplies in modular units or devicesthat may be easily inserted or removed from a housing to provide power.Providing modular power distribution modules allows power to more easilybe configured as needed for the distributed antenna system. For example,a remotely located power unit may be provided that contains a pluralityof ports or slots to allow a plurality of power distribution modules tobe inserted therein. The power unit may have ports that allow the powerto be provided over an electrical conductor medium to the RUs. Thus,when a power distribution module is inserted into the power unit in aport or slot that corresponds to a given RU, power from the powerdistribution module is supplied to the RU.

RUs may also provide wired communication ports or provide otherservices, each of which may require power consumption at the RU. Thecumulative effect of all the power consuming components at the RUs mayexceed the power provided from the remote power supply. When the powerrequirements exceed the available power, the RU may shut down andprovide no services or may have other disturbances in the operation ofthe RU.

Even when the remote power source is initially adequate to supplysufficient power to the RUs, some of the power is lost on the wirescarrying the power. Additionally, some power supplies may be set to thewrong power setting or have other malfunctions. When an RU is designedto consume power at close to the maximum power available from the remotepower supply, it becomes important to verify that the expected power isactually available at the ports of the RU. As noted above, if the poweravailable at the ports is below what is required, the RU may shut downand provide no services, or may have other disturbances in the operationof the RU.

No admission is made that any reference cited herein constitutes priorart. Applicant expressly reserves the right to challenge the accuracyand pertinency of any cited documents.

SUMMARY OF THE DETAILED DESCRIPTION

Embodiments disclosed in the detailed description include powermanagement techniques in distributed communication systems. Relatedcomponents, systems, and methods are also disclosed. In embodimentsdisclosed herein, the power available at a remote unit (RU) is measuredand compared to the power requirements of the RU. In an exemplaryembodiment, voltage and current is measured for two dummy loads at theRU and these values are used to solve for the output voltage of thepower supply and the resistance of the wires. From these values, amaximum power available may be calculated and compared to powerrequirements of the RU.

One embodiment of the disclosure relates to a RU for use in adistributed communication system. The RU is comprised of at least oneantenna configured to transmit radio frequency signals into a coveragearea. The RU is also comprised of a power unit configured to receive apower signal from a power distribution module through a power medium, apower over Ethernet integrated circuit (POE IC) configured to measurevoltage and current from the power input, and a control system. Thecontrol system is configured to open a services switch between the powerinput and a real load, to instruct the POE IC to close a first switchcoupling a first load resistance to the power input, to instruct the POEIC to measure a first voltage and a first current associated with thefirst load resistance, and to instruct the POE IC to open the firstswitch and close a second switch coupling a second load resistance tothe power input. The control system is also configured to instruct thePOE IC to measure a second voltage and a second current associated withthe second load resistance and to calculate an available power for theRU. The remote unit includes at least one antenna unit for at least oneof transmitting signals into and receiving signals from a coverage area.

An additional embodiment of the disclosure relates to a method ofmanaging power in a RU of a distributed communication system. The methodcomprises opening a services switch associated with a real load andwhile a first switch associated with a first resistance is closed,measuring a first voltage and first current associated with the firstresistance, and while a second switch associated with a secondresistance is closed, measuring a second voltage and a second currentassociated with the second resistance. The method also comprisescalculating an available power for the RU based on the first current,the first voltage, the second current and the second voltage.

An additional embodiment of the disclosure relates to a distributedcommunication system. The distributed communication system comprises aplurality of remote units. Each remote unit comprises at least oneantenna configured to transmit radio frequency signals into a coveragearea. Each RU is also comprised of a power unit configured to receive apower signal from a power distribution module through a power medium, apower over Ethernet integrated circuit (POE IC) configured to measurevoltage and current from the power input, and a control system. Thecontrol system is configured to open a services switch between the powerinput and a real load, to instruct the POE IC to close a first switchcoupling a first load resistance to the power input, to instruct the POEIC to measure a first voltage and a first current associated with thefirst load resistance, and to instruct the POE IC to open the firstswitch and close a second switch coupling a second load resistance tothe power input. The control system is also configured to instruct thePOE IC to measure a second voltage and a second current associated withthe second load resistance and to calculate an available power for theRU.

Additional features and advantages will be set forth in the detaileddescription which follows, and in part will be readily apparent to thoseskilled in the art from the description or recognized by practicing theembodiments as described in the written description and the claimshereof, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely embodiments, and areintended to provide an overview or framework to understand the natureand character of the claims.

The accompanying drawings are included to provide a furtherunderstanding, and are incorporated in and constitute a part of thisspecification. The drawings illustrate one or more embodiment(s), andtogether with the description, serve to explain principles and operationof the various embodiments.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of an exemplary distributed antennasystem;

FIG. 2A is a partially schematic cut-away diagram of an exemplarybuilding infrastructure in which the distributed antenna system in FIG.1 can be employed;

FIG. 2B is an alternative diagram of the distributed antenna system inFIG. 2A;

FIG. 3 is a schematic diagram of providing digital data services andradio frequency (RF) communication services to remote units (RUs) orother remote communications devices in the distributed antenna system ofFIG. 1;

FIG. 4 is a schematic diagram of an exemplary power distribution modulethat is supported by an exemplary power unit;

FIG. 5 is a schematic diagram of an exemplary power management moduleaccording to an exemplary embodiment of the present disclosure;

FIG. 6 is a flow chart of an exemplary process used by a powermanagement module according to FIG. 5; and

FIG. 7 is a schematic diagram of a generalized representation of anexemplary computer system that can be used for controlling the powerdistribution modules disclosed herein, wherein the exemplary computersystem is adapted to execute instructions from an exemplarycomputer-readable media.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments, examples ofwhich are illustrated in the accompanying drawings, in which some, butnot all embodiments are shown. Indeed, the concepts may be embodied inmany different forms and should not be construed as limiting herein;rather, these embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Whenever possible, like referencenumbers will be used to refer to like components or parts. Variousembodiments will be further clarified by the following examples.

Embodiments disclosed in the detailed description include powermanagement techniques in distributed communication systems. Relatedcomponents, systems, and methods are also disclosed. In embodimentsdisclosed herein, the power available at a remote unit (RU) is measuredand compared to the power requirements of the RU. In an exemplaryembodiment, voltage and current is measured for two dummy loads at theRU and these values are used to solve for the output voltage of thepower supply and the resistance of the wires. From these values, amaximum power available may be calculated and compared to powerrequirements of the RU.

While the concepts of the present disclosure are applicable to differenttypes of distributed communication systems, an exemplary embodiment isused in a distributed antenna system and this exemplary embodiment isexplored herein. Before discussing an exemplary power management system,exemplary distributed antenna systems capable of distributing radiofrequency (RF) communications signals to distributed or remote units(RUs) are first described with regard to FIGS. 1-3. It should beappreciated that in an exemplary embodiment the RUs may contain antennassuch that the RU is a remote antenna unit and may be referred to as aRAU.

In this regard, the distributed antenna systems in FIGS. 1-3 can includepower units located remotely from RUs that provide power to the RUs foroperation. Embodiments of power management modules in a distributedcommunication system, including the distributed antenna systems in FIGS.1-3, begin with FIG. 4. The distributed antenna systems in FIGS. 1-3discussed below include distribution of RF communications signals;however, the distributed antenna systems are not limited to distributionof RF communications signals. Also note that while the distributedantenna systems in FIGS. 1-3 discussed below include distribution ofcommunications signals over optical fiber, these distributed antennasystems are not limited to distribution over optical fiber. Distributionmediums could also include, but are not limited to, coaxial cable,twisted-pair conductors, wireless transmission and reception, and anycombination thereof. Also, any combination can be employed that alsoinvolves optical fiber for portions of the distributed antenna system.

In this regard, FIG. 1 is a schematic diagram of an embodiment of adistributed antenna system. In this embodiment, the system is an opticalfiber-based distributed antenna system 10. The distributed antennasystem 10 is configured to create one or more antenna coverage areas forestablishing communications with wireless client devices located in theRF range of the antenna coverage areas. The distributed antenna system10 provides RF communication services (e.g., cellular services). In thisembodiment, the distributed antenna system 10 includes head-endequipment (HEE) 12 such as a head-end unit (HEU), one or more RUs 14,and an optical fiber 16 that optically couples the HEE 12 to the RU 14.The RU 14 is a type of remote communications unit. In general, a remotecommunications unit can support wireless communications, wiredcommunications, or both. The RU 14 can support wireless communicationsand may also support wired communications through wired service port 40.The HEE 12 is configured to receive communications over downlinkelectrical RF signals 18D from a source or sources, such as a network orcarrier as examples, and provide such communications to the RU 14. TheHEE 12 is also configured to return communications received from the RU14, via uplink electrical RF signals 18U, back to the source or sources.In this regard in this embodiment, the optical fiber 16 includes atleast one downlink optical fiber 16D to carry signals communicated fromthe HEE 12 to the RU 14 and at least one uplink optical fiber 16U tocarry signals communicated from the RU 14 back to the HEE 12.

One downlink optical fiber 16D and one uplink optical fiber 16U could beprovided to support multiple channels each using wave-divisionmultiplexing (WDM), as discussed in U.S. patent application Ser. No.12/892,424 entitled “Providing Digital Data Services in OpticalFiber-based Distributed Radio Frequency (RF) Communications Systems, AndRelated Components and Methods,” incorporated herein by reference in itsentirety. Other options for WDM and frequency-division multiplexing(FDM) are disclosed in U.S. patent application Ser. No. 12/892,424, anyof which can be employed in any of the embodiments disclosed herein.Further, U.S. patent application Ser. No. 12/892,424 also disclosesdistributed digital data communications signals in a distributed antennasystem which may also be distributed in the optical fiber-baseddistributed antenna system 10 either in conjunction with RFcommunications signals or not.

The optical fiber-based distributed antenna system 10 has an antennacoverage area 20 that can be disposed about the RU 14. The antennacoverage area 20 of the RU 14 forms an RF coverage area 38. The HEE 12is adapted to perform or to facilitate any one of a number ofRadio-over-Fiber (RoF) applications, such as RF identification (RFID),wireless local-area network (WLAN) communication, or cellular phoneservice. Shown within the antenna coverage area 20 is a client device 24in the form of a mobile device as an example, which may be a cellulartelephone as an example. The client device 24 can be any device that iscapable of receiving RF communications signals. The client device 24includes an antenna 26 (e.g., a wireless card) adapted to receive and/orsend electromagnetic RF signals.

With continuing reference to FIG. 1, to communicate the electrical RFsignals over the downlink optical fiber 16D to the RU 14, to in turn becommunicated to the client device 24 in the antenna coverage area 20formed by the RU 14, the HEE 12 includes a radio interface in the formof an electrical-to-optical (E/O) converter 28. The E/O converter 28converts the downlink electrical RF signals 18D to downlink optical RFsignals 22D to be communicated over the downlink optical fiber 16D. TheRU 14 includes an optical-to-electrical (O/E) converter 30 to convertreceived downlink optical RF signals 22D back to electrical RF signalsto be communicated wirelessly through an antenna 32 of the RU 14 toclient devices 24 located in the antenna coverage area 20.

Similarly, the antenna 32 is also configured to receive wireless RFcommunications from client devices 24 in the antenna coverage area 20.In this regard, the antenna 32 receives wireless RF communications fromclient devices 24 and communicates electrical RF signals representingthe wireless RF communications to an E/O converter 34 in the RU 14. TheE/O converter 34 converts the electrical RF signals into uplink opticalRF signals 22U to be communicated over the uplink optical fiber 16U. AnO/E converter 36 provided in the HEE 12 converts the uplink optical RFsignals 22U into uplink electrical RF signals, which can then becommunicated as uplink electrical RF signals 18U back to a network orother source.

To provide further exemplary illustration of how a distributed antennasystem can be deployed indoors, FIG. 2A is provided. FIG. 2A is apartially schematic cut-away diagram of a building infrastructure 50employing an optical fiber-based distributed antenna system. The systemmay be the optical fiber-based distributed antenna system 10 of FIG. 1.The building infrastructure 50 generally represents any type of buildingin which the optical fiber-based distributed antenna system 10 can bedeployed. As previously discussed with regard to FIG. 1, the opticalfiber-based distributed antenna system 10 incorporates the HEE 12 toprovide various types of communication services to coverage areas withinthe building infrastructure 50, as an example.

For example, as discussed in more detail below, the distributed antennasystem 10 in this embodiment is configured to receive wireless RFsignals and convert the RF signals into RoF signals to be communicatedover the optical fiber 16 to multiple RUs 14. The optical fiber-baseddistributed antenna system 10 in this embodiment can be, for example, anindoor distributed antenna system (IDAS) to provide wireless serviceinside the building infrastructure 50. These wireless signals caninclude cellular service, wireless services such as RFID tracking,Wireless Fidelity (WiFi), local area network (LAN), WLAN, public safety,wireless building automations, and combinations thereof, as examples.

With continuing reference to FIG. 2A, the building infrastructure 50 inthis embodiment includes a first (ground) floor 52, a second floor 54,and a third floor 56. The floors 52, 54, 56 are serviced by the HEE 12through a main distribution frame 58 to provide antenna coverage areas60 in the building infrastructure 50. Only the ceilings of the floors52, 54, 56 are shown in FIG. 2A for simplicity of illustration. In theexample embodiment, a main cable 62 has a number of different sectionsthat facilitate the placement of a large number of RUs 14 in thebuilding infrastructure 50. Each RU 14 in turn services its own coveragearea in the antenna coverage areas 60. The main cable 62 can include,for example, a riser cable 64 that carries all of the downlink anduplink optical fibers 16D, 16U to and from the HEE 12. The riser cable64 may be routed through a power unit 70. The power unit 70 may also beconfigured to provide power to the RUs 14 via an electrical power lineprovided inside an array cable 72, or tail cable or home-run tethercable as other examples, and distributed with the downlink and uplinkoptical fibers 16D, 16U to the RUs 14. For example, as illustrated inthe building infrastructure 50 in FIG. 2B, a tail cable 80 may extendfrom the power units 70 into an array cable 82. Downlink and uplinkoptical fibers in tether cables 84 of the array cables 82 are routed toeach of the RUs 14, as illustrated in FIG. 2B. Referring back to FIG.2A, the main cable 62 can include one or more multi-cable (MC)connectors adapted to connect select downlink and uplink optical fibers16D, 16U, along with an electrical power line, to a number of opticalfiber cables 66.

With continued reference to FIG. 2A, the main cable 62 enables multipleoptical fiber cables 66 to be distributed throughout the buildinginfrastructure 50 (e.g., fixed to the ceilings or other support surfacesof each floor 52, 54, 56) to provide the antenna coverage areas 60 forthe first, second, and third floors 52, 54, and 56. In an exampleembodiment, the HEE 12 is located within the building infrastructure 50(e.g., in a closet or control room), while in another exampleembodiment, the HEE 12 may be located outside of the buildinginfrastructure 50 at a remote location. A base transceiver station (BTS)68, which may be provided by a second party such as a cellular serviceprovider, is connected to the HEE 12, and can be co-located or locatedremotely from the HEE 12. A BTS (such as BTS 68) is any station orsignal source that provides an input signal to the HEE 12 and canreceive a return signal from the HEE 12.

In a typical cellular system, for example, a plurality of BTSs isdeployed at a plurality of remote locations to provide wirelesstelephone coverage. Each BTS serves a corresponding cell and when amobile client device enters the cell, the BTS communicates with themobile client device. Each BTS can include at least one radiotransceiver for enabling communication with one or more subscriber unitsoperating within the associated cell. As another example, wirelessrepeaters or bi-directional amplifiers could also be used to serve acorresponding cell in lieu of a BTS. Alternatively, radio input could beprovided by a repeater, picocell, or femtocell as other examples.

The optical fiber-based distributed antenna system 10 in FIGS. 1-2B anddescribed above provides point-to-point communications between the HEE12 and the RU 14. A multi-point architecture is also possible as well.With regard to FIGS. 1-2B, each RU 14 communicates with the HEE 12 overa distinct downlink and uplink optical fiber pair to provide thepoint-to-point communications. Whenever an RU 14 is installed in theoptical fiber-based distributed antenna system 10, the RU 14 isconnected to a distinct downlink and uplink optical fiber pair connectedto the HEE 12. The downlink and uplink optical fibers 16D, 16U may beprovided in a fiber optic cable. Multiple downlink and uplink opticalfiber pairs can be provided in a fiber optic cable to service multipleRUs 14 from a common fiber optic cable.

For example, with reference to FIG. 2A, RUs 14 installed on a givenfloor 52, 54, or 56 may be serviced from the same optical fiber 16. Inthis regard, the optical fiber 16 may have multiple nodes where distinctdownlink and uplink optical fiber pairs can be connected to a given RU14.

The HEE 12 may be configured to support any frequencies desired,including but not limited to US FCC and Industry Canada frequencies(824-849 MHz on uplink and 869-894 MHz on downlink), US FCC and IndustryCanada frequencies (1850-1915 MHz on uplink and 1930-1995 MHz ondownlink), US FCC and Industry Canada frequencies (1710-1755 MHz onuplink and 2110-2155 MHz on downlink), US FCC frequencies (698-716 MHzand 776-787 MHz on uplink and 728-746 MHz on downlink), EU R & TTEfrequencies (880-915 MHz on uplink and 925-960 MHz on downlink), EU R &TTE frequencies (1710-1785 MHz on uplink and 1805-1880 MHz on downlink),EU R & TTE frequencies (1920-1980 MHz on uplink and 2110-2170 MHz ondownlink), US FCC frequencies (806-824 MHz on uplink and 851-869 MHz ondownlink), US FCC frequencies (896-901 MHz on uplink and 929-941 MHz ondownlink), US FCC frequencies (793-805 MHz on uplink and 763-775 MHz ondownlink), and US FCC frequencies (2495-2690 MHz on uplink anddownlink).

FIG. 3 is a schematic diagram of another exemplary optical fiber-baseddistributed antenna system 90 that may be employed according to theembodiments disclosed herein to provide RF communication services. Inthis embodiment, the optical fiber-based distributed antenna system 90includes optical fiber for distributing RF communication services. Theoptical fiber-based distributed antenna system 90 in this embodiment iscomprised of three (3) main components. One or more radio interfacesprovided in the form of radio interface modules (RIMs) 92(1)-92(M) inthis embodiment are provided in HEE 94 to receive and process downlinkelectrical RF communications signals prior to optical conversion intodownlink optical RF communications signals. The RIMs 92(1)-92(M) provideboth downlink and uplink interfaces. The processing of the downlinkelectrical RF communications signals can include any of the processingpreviously described above in the HEE 12 in FIGS. 1-2A. The notation“1-M” indicates that any number of the referenced component, 1-M may beprovided. The HEE 94 is configured to accept a plurality of RIMs92(1)-92(M) as modular components that can easily be installed andremoved or replaced in the HEE 94. In one embodiment, the HEE 94 isconfigured to support up to eight (8) RIMs 92(1)-92(M).

With continuing reference to FIG. 3, each RIM 92(1)-92(M) can bedesigned to support a particular type of radio source or range of radiosources (i.e., frequencies) to provide flexibility in configuring theHEE 94 and the optical fiber-based distributed antenna system 90 tosupport the desired radio sources. For example, one RIM 92 may beconfigured to support the Personal Communication Services (PCS) radioband. Another RIM 92 may be configured to support the 700 MHz radioband. In this example, by inclusion of these RIMs 92, the HEE 94 wouldbe configured to support and distribute RF communications signals onboth PCS and LTE 700 radio bands. RIMs 92 may be provided in the HEE 94that support any frequency bands desired, including but not limited tothe US Cellular band, PCS band, Advanced Wireless Services (AWS) band,700 MHz band, Global System for Mobile communications (GSM) 900, GSM1800, and Universal Mobile Telecommunication System (UMTS). RIMs 92 maybe provided in the HEE 94 that support any wireless technologiesdesired, including but not limited to Code Division Multiple Access(CDMA), CDMA200, 1×RTT, Evolution-Data Only (EV-DO), UMTS, High-speedPacket Access (HSPA), GSM, General Packet Radio Services (GPRS),Enhanced Data GSM Environment (EDGE), Time Division Multiple Access(TDMA), Long Term Evolution (LTE), iDEN, and Cellular Digital PacketData (CDPD). RIMs 92 may be provided in the HEE 94 that support anyfrequencies desired referenced above as non-limiting examples.

With continuing reference to FIG. 3, the downlink electrical RFcommunications signals are provided to a plurality of optical interfacesprovided in the form of optical interface modules (OIMs) 96(1)-96(N) inthis embodiment to convert the downlink electrical RF communicationssignals into downlink optical RF communications signals 100D. Thenotation “1-N” indicates that any number of the referenced component 1-Nmay be provided. The OIMs 96 may be configured to provide one or moreoptical interface components (OICs) that contain O/E and E/O converters,as will be described in more detail below. The OIMs 96 support the radiobands that can be provided by the RIMs 92, including the examplespreviously described above. Thus, in this embodiment, the OIMs 96 maysupport a radio band range from 400 MHz to 2700 MHz, as an example, soproviding different types or models of OIMs 96 for narrower radio bandsto support possibilities for different radio band-supported RIMs 92provided in the HEE 94 is not required. Further, the OIMs 96 may beoptimized for sub-bands within the 400 MHz to 2700 MHz frequency range,such as 400-700 MHz, 700 MHz-1 GHz, 1 GHz-1.6 GHz, and 1.6 GHz-2.7 GHz,as examples.

The OIMs 96(1)-96(N) each include E/O converters to convert the downlinkelectrical RF communications signals to downlink optical RFcommunications signals 100D. The downlink optical RF communicationssignals 100D are communicated over downlink optical fiber(s) to aplurality of RUs 102(1)-102(P). The notation “1-P” indicates that anynumber of the referenced component 1-P may be provided. O/E convertersprovided in the RUs 102(1)-102(P) convert the downlink optical RFcommunications signals 100D back into downlink electrical RFcommunications signals, which are provided over downlinks coupled toantennas 104(1)-104(P) in the RUs 102(1)-102(P) to client devices 24(shown in FIG. 1) in the reception range of the antennas 104(1)-104(P).

E/O converters are also provided in the RUs 102(1)-102(P) to convertuplink electrical RF communications signals received from client devicesthrough the antennas 104(1)-104(P) into uplink optical RF communicationssignals 100U to be communicated over uplink optical fibers to the OIMs96(1)-96(N). The OIMs 96(1)-96(N) include O/E converters that convertthe uplink optical RF communications signals 100U into uplink electricalRF communications signals that are processed by the RIMs 92(1)-92(M) andprovided as uplink electrical RF communications signals. Downlinkelectrical digital signals 108D(1)-108D(P) communicated over downlinkelectrical medium or media (hereinafter “medium”) 110D are provided tothe RUs 102(1)-102(P), separately from the RF communication services, aswell as uplink electrical digital signals 108U(1)-108U(P) communicatedover uplink electrical medium 110U, as also illustrated in FIG. 3. Powermay be provided in the downlink and/or uplink electrical medium 110Dand/or 110U to the RUs 102(1)-102(P).

In one embodiment, up to thirty-six (36) RUs 102 can be supported by theOIMs 96, three RUs 102 per OIM 96 in the optical fiber-based distributedantenna system 90 in FIG. 3. The optical fiber-based distributed antennasystem 90 is scalable to address larger deployments. In the illustratedoptical fiber-based distributed antenna system 90, the HEE 94 isconfigured to support up to thirty six (36) RUs 102 and fit in 6U rackspace (U unit meaning 1.75 inches of height). The downlink operationalinput power level can be in the range of −15 dBm to 33 dBm. Theadjustable uplink system gain range can be in the range of +15 dB to −15dB. The RF input interface in the RIMs 92 can be duplexed and simplex,N-Type. The optical fiber-based distributed antenna system can includesectorization switches to be configurable for sectorization capability,as discussed in U.S. patent application Ser. No. 12/914,585 filed onOct. 28, 2010, and entitled “Sectorization In Distributed AntennaSystems, and Related Components and Method,” which is incorporatedherein by reference in its entirety.

In another embodiment, an exemplary RU 102 may be configured to supportup to four (4) different radio bands/carriers (e.g. ATT, VZW, TMobile,Metro PCS: 700LTE/850/1900/2100). Radio band upgrades can be supportedby adding remote expansion units over the same optical fiber (or upgradeto MIMO on any single band). The RUs 102 and/or remote expansion unitsmay be configured to provide external filter interface to mitigatepotential strong interference at 700 MHz band (Public Safety, CH51,56);Single Antenna Port (N-type) provides DL output power per band (Lowbands (<1 GHz): 14 dBm, High bands (>1 GHz): 15 dBm); and satisfies theUL System RF spec (UL Noise Figure: 12 dB, UL IIP3: −5 dBm, UL AGC: 25dB range).

As further illustrated in FIG. 3, a power supply module (PSM) 118 mayprovide power to the RIMs 92(1)-92(M) and radio distribution cards(RDCs) 112 that distribute the RF communications from the RIMs92(1)-92(M) to the OIMs 96(1)-96(N) through RDCs 114. In one embodiment,the RDCs 112, 114 can support different sectorization needs. A PSM 120may also be provided to provide power to the OIMs 96(1)-96(N). Aninterface 116, which may include web and network management system (NMS)interfaces, may also be provided to allow configuration andcommunication to the RIMs 92(1)-92(M) and other components of theoptical fiber-based distributed antenna system 90. A microcontroller,microprocessor, or other control circuitry, called a head-end controller(HEC) 122 may be included in HEE 94 to provide control operations forthe HEE 94.

RUs, including the RUs 14, 102 discussed above, contain power-consumingcomponents for transmitting and receiving RF communications signals. Inthe situation of an optical fiber-based distributed antenna system, theRUs 14, 102 may contain O/E and E/O converters that also require powerto operate. As an example, a RU 14, 102 may contain a power unit thatincludes a power supply to provide power to the RUs 14, 102 locally atthe RU 14, 102. Alternatively, power may be provided to the RUs 14, 102from power supplies provided in remote power units such as power units70. In either scenario, it may be desirable to provide these powersupplies in modular units or devices that may be easily inserted orremoved from a power unit. Providing modular power distribution modulesallows power to more easily be configured as needed for the distributedantenna system.

In this regard, FIG. 4 is a schematic diagram of an exemplary powerdistribution module 130 that can be employed to provide power to the RUs14, 102 or other power-consuming DAS components, including thosedescribed above. In this embodiment, the power distribution module 130may be the power unit 70 previously described above to remotely providepower to the RUs 14, 102. The power unit 70 may be comprised of achassis or other housing that is configured to support powerdistribution modules 130. The power distribution module 130 may includea power supply unit 132 that has a plurality of outputs 134, 136. Theoutput 134 may be connected to a port 138. In an exemplary embodiment,the port 138 is a multi-connector port configured to accommodate aconventional plug such as a CAT 5 or CAT 6 plug and includes conductiveelements configured to carry power.

The output 136 may have a reduced voltage relative to output 134 (e.g.,12 V compared to 56 V) and be coupled to a fan 140 with associated fanmonitor 142 and fan alarm 144. The port 138 may further includeconductive elements 146 configured to carry return signals from the RU14, 102. While FIG. 4 illustrates an exemplary power distribution module130, it should be appreciated that other power supply configurations maybe used with embodiments of the present disclosure.

The power distribution module 130 provides power to the RU 102 throughthe electrical medium 110 as shown in FIG. 3 or 5. As illustrated inFIG. 5, the electrical medium 110 has a resistance R_(LINE) 149 whichdissipates power thereby reducing the power that is available at the RU102. The present disclosure provides, in exemplary embodiments, systemsand techniques through which the power available at the RU 102 may becalculated and appropriate remedial action (if any) taken. Inparticular, in an exemplary embodiment, an alarm may be generated sothat correction may be made. One such alarm may be a local light beingilluminated. An alternate alarm may be a report via a management ortelemetry channel to a central management system. In another exemplaryembodiment, the RU 102 may prioritize services provided by the RU 102and shut down lower priority services to prevent the other servicessupported by RU 102 from shutting down or having other anomalous andundesired operational behavior. In still another alternate andnon-exclusive embodiment, the resistance value of R_(LINE) 149 may bereported to a central facility for future planning purposes. That is,the system operators may review the R_(LINE) 149 value when evaluatingwhether a potential upgrade is feasible at a particular RU 102. Forexample, if R_(LINE) 149 is high and there are already several servicesat a particular RU 102, then it may not be practical to add a service tothat RU 102 unless an additional power source is provided. Still otherplanning decisions can be made as desired.

In this regard, the RU 102 includes a controller 150 and a power overEthernet integrated circuit (POE IC) 152. In an exemplary embodiment,the POE IC may be the LTC4266IUHF#PBF sold by Linear Technology of 1630McCarthy Blvd. Milpitas, Calif. 95035-7417. At the time of writing, thespecification for this part was available atwww.linear.com/product/LTC4266 and the datasheet was available atcds.linear.com/docs/en/datasheet/4266fd.pdf. The datasheet is hereinincorporated by reference in its entirety. Other POE IC may also beused.

With continued reference to FIG. 5, the RU 102 includes a “real” load154 selectively coupled to incoming power via switch 156. Switch 156 issometimes referred to herein as a services switch. The “real” load 154may include the O/E and E/O converters, RF transceivers, processors, andother elements that provide the primary services and functionality ofthe RU 102. The services may include cellular services such as thoseenumerated above, radio frequency communication services, WiFi,Ethernet, location based services, and the like. The services may beembodied in separate modules, separate circuit boards, antennas, or thelike. As these services are conventional, further explanation of them isomitted. The switch 156 is operatively controlled by the controller 150.

With continued reference to FIG. 5, POE IC 152 includes a current sensorand a voltage sensor. When it is desired to calculate the availablepower at the RU 102, and specifically Pin at ports 158, 160, thecontroller 150 disconnects the “real” load 154 by opening switch 156 andinstructs the POE IC 152 to close switch 162 and connect load R_(L1) 164to the ports 158, 160 through the current sensing resistor R_(s1) 166.The POE IC 152 then measures the voltage on the sensing resistor R_(s1)166 and the voltage V_(in1) at the nodes 168, 170, where V_(in1)=V⁺−V⁻.Note that the nodes 168, 170 correspond to the ports 158, 160. Since theresistance of sensing resistor R_(s1) 166 is known, the current I₁ canbe calculated by the ratio between the voltage measured on the resistorto the resistance of the resistor. Based on this truth, the followingequation can be formulated.V _(in1) =V _(out) −I ₁ *R _(LINE)  (1)

With continued reference to FIG. 5, the controller 150 then instructsthe POE IC 152 to open switch 162 and close switch 172, which connectsload R_(L2) 174 to the ports 158, 160 through the current sensingresistor R_(s2) 176. The POE IC 152 then measures the voltage on thesensing resistor R_(s2) 176 and the voltage V_(in2) at the nodes 168,170, where V_(in2)=V⁺−V⁻. Since the resistance of sensing resistorR_(s2) 176 is known, the current I₂ can be calculated by the ratiobetween the voltage measured on the resistor to the resistance of theresistor. Based on this truth, the following equation can be formulated.V _(in2) =V _(out) −I ₂ *R _(LINE)  (2)

By simultaneous solution of Eq. 1 and Eq. 2, V_(out) and R_(LINE) can befound. Then the available power at the ports 158, 160 can be calculatedfor any given current consumption I by solving:P _(in) =I*V _(out) −I ² *R _(LINE)  (3)

When the process is finished, both switches 162, 172 are opened andswitch 156 may be closed for normal operation. If the power P_(in) isnot sufficient for the operating of the “real” load 154, the RU 102 maydisconnect some lower priority services within the “real” load 154. Inan exemplary embodiment, R_(L1) 164 and R_(L2) 174 are 4.7 kΩ and 680Ωrespectively. Note that these values are exemplary and may vary asneeded or desired, although in general, a resistance of at least 650Ω isrequired coupled with enough spacing between the values for resistors164, 174 for a meaningful measurement to be made. Thus, the exemplaryvalues for these resistances may vary by about 10%. These values for theresistors 164, 174 are chosen to allow the power dissipated during thecurrent and voltage measurements to meet the pulse power rating of thepower resistors 164, 174 and not be physically too large within thedevice. In an exemplary embodiment, the resistors are the PWC2010-4K7JIand the PWC2010-680RI sold by TT Electronics of Clive House, 12-18Queens Road, Weybridge, Surrey, KT13 9XB, England.

While the above explanation sets forth the process through which theavailable power may be calculated, FIG. 6 provides a flow chart of theprocess 180 more explicitly. The process 180 begins when the “real” load154 having services and functions and POE IC 152 are installed in the RU102 (block 182). Note that installation of such services may be a newinstallation of a new RU 102 or an additional service being added to anexisting and previously deployed RU 102. In an exemplary embodiment,power will have been disconnected from the RU 102 or not yet have beenattached. Accordingly, the power is connected to the RU 102 (block 184).

With continued reference to FIG. 6, the controller 150 opens the switch156 and closes (through the POE IC 152) switch 162 (block 186). Statedanother way, the controller 150 deactivates all services and functionsof the RU 102 (except the power sensing process herein described) byopening the switch 162. The controller 150 then measures, using the POEIC 152, the current I₁ and the voltage V_(in1) (block 188). Thecontroller 150 then opens switch 162 and closes switch 172 (block 190).The controller 150 measures, through POE IC 152, the current I₂ and thevoltage V_(in2) (block 192). From the two measurements, the controller150 may calculate the maximum power available P_(in) at the RU 102(block 194). The calculation is a function of two equations with twounknowns and becomes a routine solution as shown above.

With continued reference to FIG. 6, the controller 150 can compareavailable P_(in) to the expected power demands of the “real” load 154(block 196). If the answer to the comparison is positive, that there isenough power, then the RU 102 may operate normally (block 198). If,however, the answer is negative, that the power required by the “real”load 154 exceeds P_(in), then the controller 150 may take remedialaction (block 200).

In exemplary embodiments, remedial actions include reducing transmissionpower of one or more of the services or functions within the “real” load154, shutting off completely one or more of the services or functionswithin the “real” load 154, or generating an alarm. As noted above, thecalculated R_(LINE) may also be reported and saved for future planningpurposes.

In an alternate embodiment, the power supply output voltage V_(OUT) maybe known (from direct measurement, prior calculations, or the like) inwhich case only a single equation is needed to solve for the unknownvariable R_(LINE). Having to solve for only one variable means that onlyone equation is needed.

FIG. 7 is a schematic diagram representation of additional detailregarding an exemplary computer system 400 that may be included in thepower distribution module 130 or the RU 102. The computer system 400 isadapted to execute instructions from an exemplary computer-readablemedium to perform power management functions. In this regard, thecomputer system 400 may include a set of instructions for causing thecontroller 150 to enable and disable the services or functions withinthe “real” load 154, as previously described. The RU 102 or powerdistribution module 130 may be connected (e.g., networked) to othermachines in a LAN, an intranet, an extranet, or the Internet. The RU 102or power distribution module 130 may operate in a client-server networkenvironment, or as a peer machine in a peer-to-peer (or distributed)network environment. While only a single device is illustrated, the term“device” shall also be taken to include any collection of devices thatindividually or jointly execute a set (or multiple sets) of instructionsto perform any one or more of the methodologies discussed herein. Thecontroller 150 may be a circuit or circuits included in an electronicboard card, such as a printed circuit board (PCB) as an example, aserver, a personal computer, a desktop computer, a laptop computer, apersonal digital assistant (PDA), a computing pad, a mobile device, orany other device, and may represent, for example, a server or a user'scomputer.

The exemplary computer system 400 in this embodiment includes aprocessing device or processor 402, a main memory 414 (e.g., read-onlymemory (ROM), flash memory, dynamic random access memory (DRAM) such assynchronous DRAM (SDRAM), etc.), and a static memory 406 (e.g., flashmemory, static random access memory (SRAM), etc.), which may communicatewith each other via the data bus 408. Alternatively, the processingdevice 402 may be connected to the main memory 414 and/or static memory406 directly or via some other connectivity means. The processing device402 may be a controller, and the main memory 414 or static memory 406may be any type of memory.

The processing device 402 represents one or more general-purposeprocessing devices such as a microprocessor, central processing unit, orthe like. More particularly, the processing device 402 may be a complexinstruction set computing (CISC) microprocessor, a reduced instructionset computing (RISC) microprocessor, a very long instruction word (VLIW)microprocessor, a processor implementing other instruction sets, orprocessors implementing a combination of instruction sets. Theprocessing device 402 is configured to execute processing logic ininstructions 404 for performing the operations and steps discussedherein.

The computer system 400 may further include a network interface device410. The computer system 400 also may or may not include an input 412 toreceive input and selections to be communicated to the computer system400 when executing instructions. The computer system 400 also may or maynot include an output 422, including but not limited to a display, avideo display unit (e.g., a liquid crystal display (LCD) or a cathoderay tube (CRT)), an alphanumeric input device (e.g., a keyboard), and/ora cursor control device (e.g., a mouse).

The computer system 400 may or may not include a data storage devicethat includes instructions 416 stored in a computer-readable medium 418.The instructions 424 may also reside, completely or at least partially,within the main memory 414 and/or within the processing device 402during execution thereof by the computer system 400, the main memory 414and the processing device 402 also constituting computer-readable medium418. The instructions 416, 424 may further be transmitted or receivedover a network 420 via the network interface device 410.

Many modifications and other embodiments of the embodiments set forthherein will come to mind to one skilled in the art to which theembodiments pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. For example, thedistributed antenna systems could include any type or number ofcommunications mediums, including but not limited to electricalconductors, optical fiber, and air (i.e., wireless transmission). Thedistributed antenna systems may distribute any type of communicationssignals, including but not limited to RF communications signals anddigital data communications signals, examples of which are described inpreviously incorporated U.S. patent application Ser. No. 12/892,424.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is no way intended thatany particular order be inferred.

It will be apparent to those skilled in the art that variousmodifications and variations can be made without departing from thespirit or scope of the invention. Since modifications combinations,sub-combinations and variations of the disclosed embodimentsincorporating the spirit and substance of the invention may occur topersons skilled in the art, the invention should be construed to includeeverything within the scope of the appended claims and theirequivalents.

What is claimed is:
 1. A remote unit for use in a distributedcommunication system, comprising: at least one antenna configured totransmit radio frequency signals into a coverage area; a power inputconfigured to receive a power signal from a power distribution modulethrough a power medium; a power over Ethernet integrated circuit (POEIC) configured to measure voltage and current from the power input; anda control system configured to: open a services switch between the powerinput and a real load; instruct the POE IC to close a first switchcoupling a first load resistance to the power input; instruct the POE ICto measure a first voltage and a first current associated with the firstload resistance; instruct the POE IC to open the first switch and closea second switch coupling a second load resistance to the power input;instruct the POE IC to measure a second voltage and a second currentassociated with the second load resistance; and calculate an availablepower for the remote unit.
 2. The remote unit of claim 1, furthercomprising the services switch, the first switch, and the second switch.3. The remote unit of claim 1, wherein the POE IC comprises a currentsensor.
 4. The remote unit of claim 1, wherein the POE IC comprises avoltage sensor.
 5. The remote unit of claim 1, wherein the remote unitis configured to receive communication signals from a fiberinfrastructure.
 6. The remote unit of claim 1, wherein the controlsystem is configured to generate an alert if the available power isinsufficient for all services at the remote unit.
 7. The remote unit ofclaim 1, wherein the control system is further configured to shut off aservice if the available power is insufficient for all services.
 8. Theremote unit of claim 1, wherein the control system is further configuredto reduce transmission power for one or more services if the availablepower is insufficient for all services.
 9. The remote unit of claim 1,wherein: the POE IC comprises at least one of a current sensor and avoltage sensor; the control system is configured to reduce transmissionpower for one or more services if the available power is insufficientfor all services; and the remote unit comprises a plurality of servicemodules configured to provide the services at the remote unit, theplurality of service modules comprising service modules selected fromthe group consisting of: cellular service, radio frequencycommunications, WiFi, Ethernet, and location based services.
 10. Theremote unit of claim 1, further comprising a plurality of servicemodules configured to provide services at the remote unit.
 11. Theremote unit of claim 10, wherein the plurality of service modulescomprises service modules selected from the group consisting of:cellular service, radio frequency communications, WiFi, Ethernet, andlocation based services.
 12. The remote unit of claim 1, wherein thefirst load resistance comprises approximately 680Ω and the second loadresistance comprises approximately 4.7 kΩ.
 13. A method of managingpower in a remote unit of a distributed communication system, the methodcomprising: opening a services switch associated with a real load; whilea first switch associated with a first resistance is closed, measuring afirst voltage and a first current associated with the first resistance;while a second switch associated with a second resistance is closed,measuring a second voltage and a second current associated with thesecond resistance; and calculating an available power for the remoteunit based on the first current, the first voltage, the second current,and the second voltage.
 14. The method of claim 13, further comprisingclosing the first switch after opening the services switch.
 15. Themethod of claim 13, further comprising opening the first switch aftermeasuring the first voltage and the first current.
 16. The method ofclaim 13, further comprising closing the second switch after opening theservices switch.
 17. The method of claim 13, further comprising openingthe second switch after measuring the second voltage and the secondcurrent.
 18. The method of claim 17, further comprising closing theservices switch after opening the second switch.
 19. The method of claim13, wherein measuring comprises measuring with sensors within a powerover Ethernet integrated circuit (POE IC).
 20. A distributedcommunication system, comprising a plurality of remote units, eachremote unit comprising: at least one antenna configured to transmitradio frequency signals into a coverage area; a power input configuredto receive a power signal from a power distribution module through apower medium; a power over Ethernet integrated circuit (POE IC)configured to measure voltage and current from the power input; and acontrol system configured to: open a services switch between the powerinput and a real load; instruct the POE IC to close a first switchcoupling a first load resistance to the power input; instruct the POE ICto measure a first voltage and a first current associated with the firstload resistance; instruct the POE IC to open the first switch and closea second switch coupling a second load resistance to the power input;instruct the POE IC to measure a second voltage and a second currentassociated with the second load resistance; and calculate an availablepower for the remote unit.